Rihanna reigned supreme as the most-mentioned artist of the three-day festival after assisting Eminem on three songs. Together, they earned the most-tweeted moment. Rounding out the most-mentioned artists are Lorde, Martin Garrix and Arctic Monkeys, according to data that Twitter shared with Mashable on Monday.

Here are five moments that had people talking both at the event and online.

1. Eminem and Special Guest Rihanna Join Forces

Long before he took to the stage, everyone knew Eminem was going to make his headlining set the one to see on Friday night. Thankfully, Slim Shady did not disappoint.

Frequent collaborator and future touring partner Rihanna joined the rapper for several songs, including number one hits "Love The Way You Lie" and "The Monster." On top of that, RiRi also sang Dido's part on stalker-fan hit "Stan." While Em also brought out his Bad Meets Evil bandmate Royce Da 5'9", Rihanna demanded the spotlight.

Chance the Rapper

Caleb Followill of Kings of Leon

Donald Glover of Childish Gambino

Betty Who

Nelly

Image: Daniel Boczarski/Getty Images

Yasmine Yousaf of Krewella

Image: Timothy Hiatt/WireImage

Outkast

Image: Josh Brasted/FilmMagic

Calvin Harris

Image: Barry Brecheisen/WireImage

While there were EDM producers and indie rock bands in spades, hip-hop had the buzziest moments this year. After Eminem and Rihanna, Outkast's performance was the second biggest topic of discussion, both on the ground and online.

Big Boi and Andre 3000 have been playing festivals all summer, and they’ve gotten into a pretty good routine. In fact, the duo's performance at Lolla was almost identical to their showing at Governor's Ball in New York in June, but no one seemed to mind.

3. The Rain

Lollapalooza attendees brave the rain at Grant Park in Chicago on Aug. 3.

Friday and Saturday had nice weather, but it wouldn't be a summer festival without a little rain. Sunday saw intermittent downpours, but performers and fans didn't let it ruin the show.

Childish Gambino and Cage the Elephant went out of their way to get wet, leaving the stage and roaming into the audience. While some festival-goers did seek shelter, many embraced the rain and enjoyed sliding around in the mud.

4. Dev Hynes Tweets About Being Assaulted

Dev Hynes of Blood Orange filled headlines when he was reportedly assaulted by Lollapalooza security guards. After his set, he tweeted Friday that three men grabbed him and his girlfriend, Samantha Urbani, threw them to the ground, and hit them. He went on to ask people who had seen the incident to speak out, as he plans on pressing charges.

Hynes was wearing a homemade T-shirt emblazoned with the names Trayvon Martin, Jordan Davis and Eric Garner— — all victims of police brutality — during his performance. Urbani's shirt said "STOP POLICE BRUTALITY."

I gave a speech on racism and police brutality and then I am jumped by three security guards and my gf is assaulted. @lollapalooza

Lollapalooza officials released a statement on Monday saying that they are investigating the matter with authorities and that they care care about everyone's safety at the festival.

5. Headliner Calvin Harris Lights Up the Sky

EDM hitmaker Calvin Harris pulled out all of the stops to ensure people attending his headlining set had the time of their lives, using steam, lasers and fire to bring his stage to life.

He played incredible mix of well-known singles ("Sweet Nothing," "Summer" and "We Found Love," though no Rihanna this time), as well as his equally-as-excellent instrumental tracks and several remixes.

And just as the beat dropped on a select few favorites, fireworks shot out from the top of his stage and lit up the screaming crowd.

8 Lollapalooza Non-Headliners You Must to Hear

1. Hozier, "Take Me To Church"

A sensation already in his home country of Ireland, Hozier's deeply moving "Take Me To Church" is the kind of breakout hit that cannot be ignored. Like a male Adele, his voice is overflowing with soul and a certain kind of sadness. He says more with his incredible vocal style than his lyrics. With much of his output being on the darker side, you do need to be in a certain mood to really get what he's saying, but when you do ... look out.

2. Vic Mensa, "Down On My Luck"

Vic Mensa is the perfect mix of everything that makes a big hit. He has a ridiculously smooth flow and he pairs it with '90s dance beats, creating instantly infectious hooks. "Down On My Luck" is his first major single, and what a way to introduce yourself to the masses. The track picks up where Azealia Banks left off with "1991" and throws you back to the days of La Bouche (remember "Be My Lover"?), which we all sorely miss.

3. Bebe Rexha, "I Can't Stop Drinking About You"

Bebe Rexha has been working with major names in the industry for years, and her time to shine is just around the corner. After fronting Black Cards, the side project of Fall Out Boy's Pete Wentz, Rexha went on to write Eminem and Rihanna's "Monster" as well as album tracks for the likes of Madonna and Selena Gomez. You heard her most recently on Cash Cash's "Take Me Home," and you’re going to love her own "I Can’t Stop Drinking About You."

4. Johnnyswim, "Home"

Married couple Amanda Sudano and Abner Ramirez have been quietly making their name in the underground music world for years now, and with the release of their debut album Diamonds, the world is starting to catch on. The duo is popular in the alt-country field, and now that The Civil Wars have disbanded, Johnnyswim might become the new favorite duo. If you don't think country is your thing, you should still give them a go. This isn't your typical whiskey and trucks kind of show.

5. London Grammar, "Hey Now"

Lead singer Hannah Reid's haunting vocals are enough to create a star, but thankfully London Grammar has the entire package. A perfect mix of expertly-timed guitar work and incredible beats, the band has made a name for itself by creating an entirely original style of music we didn't know we were missing. After guesting on Disclosure's hit "Help Me Lose My Mind," the band went on to find success in the UK, racking up several top 40 hits. While it's hard to decide if their music is best suited for a club or a lounge, its beauty is undeniable.

6. Wallpaper, "Hesher"

Wallpaper a.k.a. Ricky Reed, is another notable name behind the scenes working on breaking into the mainstream. His production specialty is twisted, dirty horns, which you can hear in some of the biggest hits this summer. After crafting hits for Far East Movement in the UK, he found success stateside composing Jason Derulo's "Talk Dirty" and "Wiggle." Reed is poised to fill the void Kesha left when she dropped the $. Pop music will always need someone to encourage drinking until you pass out.

7. Smallpools, "Dreaming"

Los Angeles-based pop rock foursome Smallpools is still fairly new to the scene, but they are already one of the most buzzed-about bands out there. From the moment they released "Dreaming," it was obvious they were going to become popular, and fast. The band has amazing pop sensibilities, and they create some of the happiest music out there. If you’'e a fan of Passion Pit, this one's for you.

8. Royal Blood, "Little Monster"

While dance and electronic pop may be dominating the charts these days, there's always room for a great rock band. Right now it seems the UK is producing some of the best newcomers to the genre, and Royal Blood is one to know. The duo has opened for the Arctic Monkeys and was named by the BBC as a group that will define the sound of the year. "Little Monster" is a hard track with incredible guitar riffs -- the kind of thing you just don't hear enough of anymore.

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